Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Christopher needs to master at least $130$ songs. Christopher has already mastered $7$ songs. If Christopher can master $10$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
To solve this, let's set up an expression to show how many songs Christopher will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Christopher Needs to have at least $130$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 130$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 130$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 10 + 7 \geq 130$ $ x \cdot 10 \geq 130 - 7 $ $ x \cdot 10 \geq 123 $ $x \geq \dfrac{123}{10} \approx 12.30$ Since we only care about whole months that Christopher has spent working, we round $12.30$ up to $13$ Christopher must work for at least 13 months.